The invention relates to a method for producing a steel shaped body, particularly, for example, a component for common rail fuel injection valves.
Steel blanks can be produced by means of smelting metallurgy methods. The raw material in the steel plant consisting of pig iron is smelted via the LD-route or consisting of scrap iron via the so-called electric furnace route, and the desired composition is thereby adjusted in the molten state. After that smelting process, such a steel blank is continuously cast to precursor material in continuous casting plants, which is subsequently rolled out to bar steel in the rolling mill using thermomechanical rolling technology with or without heat treatment subsequently taking place in a targeted manner. The bar steel is then used as the starting material for the metal-cutting manufacturing of corresponding components.
Near-net-shape manufacturing processes, with which metallic components can be produced, are known as powder metallurgical manufacturing processes. This relates to pressing and the subsequent sintering of metallic powders or also to the so-called hot isostatic pressing (HIP). The so-called metal powder injection molding or MIM (metal injection molding) constitutes a special form. Metallic powders, which are pre-alloyed corresponding to the desired target composition, are thereby used as a starting basis.
A method for manufacturing metal bodies is known from the European patent publication EP 1 268 105 B1. In this method, metal compound particles are mixed with a binder and pressed to formed components. The binder is subsequently removed and the metal compound is reduced to metal by means of a gas flush with reducing gas at high temperatures, wherein the reduction is carried out at temperatures below the sinter temperature of the reduced metal compound and a binder mixture consisting of a removable and a stable component is used, whereupon the removable component is extracted. The shaped body is subsequently subjected to a temperature of between 550° C. and 95° C. in oxidizing atmospheres, and the stable binder content is thereby converted into gaseous decomposition products and removed from the matrix, whereupon the shaped body is pre-reduced in atmospheres containing carbon and subsequently post-reduced with gas containing hydrogen. This prior art, however, does not explicitly relate to the production of bainitically formed steel shaped bodies having an intrinsically pronounced stability.